The sea ice in the Arctic Ocean has melted to its smallest ever level in the latest dramatic sign of the longterm impact of global warming, US researchers say.

Scientists at the University of Colorado at Boulder said data recorded on Sunday broke the 2007 record for the lowest extent of sea ice and that the mel shoe shops t could become even more significant with several weeks of summer left to go.

The National Snow and Ice Data Center at the university said in a statement that the decline in summer Arctic sea ice is considered a strong signal of longterm climate warming.

The sea ice fell to 4.10 million square kilometres, some 70,000sq km less than the earlier record charted on September 18, 2007, the centre said.

Mark Serreze, director of the centre, said the record was all the more striking as 2007 had near perfect patterns for melting ice, but that the weather this year was unremarkable other than a storm in early August.

The ice is so thin and weak now, it doesnt matter how the winds blow, Serreze said in the statement.

Walt Meier, a scientist at the centre, said the record was on one level just a number, and occa shoe shops sionally records are going to get set.

But in the context of whats happened in the last several years and throughout the satellite record, its an indication that the Arctic sea ice cover is fundamentally changing, he said.

The planet has charted a slew of record temperatures in recent years, with 13 of the warmest years ever taking place in the past decade and a half.

Scientists say climate change is largely caused by human emissions of carbon and other greenhouse gases, which hinder the planets reflection of the suns heat back into space.

The melting of Arctic sea ice has helped open up new shipping lanes but is also believed to hold serious consequenc shoe shops es for the rest of the planet as the ice serves a vital function in keeping the planet cool. shoe shops